Polarized electromagnetic relay



July 3, 1951 R. E. H. CARPENTER 2,559,399

POLARIZED ELECTROMAGNETIC RELAY Filed Sept. 22, 1947 2 Sheets-Sheet 1F/G- 5 32 O 18 5 6 I l 33 3/ /O n 9 ll I I a 3 1 25 I l I 2/ 27 I I 2223 2 Inventor I lb 6 Ro er) E. H. Carpehfer Attorney July 3, 1951 FiledSept. 22. 1947 R. E. H. CARPENTER POLARIZED ELECTROMAGNETIC RELAY 2Sheets-Sheet 2 I n u entor Atlorney Patented July 3, 1951 POLARIZEDELECTROMAGNETIC RELAY Rupert Evan Howard Carpenter, South Croydon,England Application September 22, 1947, Serial No. 775,455 In GreatBritain October 2, 1946 Claims.

This invention relates to polarised electromagnetic relays and likemagnetic devices for the interconversion of electrical and mechanicalvibrations and one of the chief objects of the invention is to provide aform of relay which is of very small dimensions so as to occupy a smallspace and to be light in weight without materially Sacrificing theefiiciency of the instrument. While, however, the invention is valuablein its application to polarised telegraph relays, it is equallyapplicable to any electromagnetic relays which need to be set up in arelatively small space and in which the minimum of weight is animportant consideration.

The qualities outlined above are attained, according to the invention,by employing two magnetic pole-pieces rigidly secured together andhaving an armature mounted so as to vibrate between them while eachpole-piece has three 00- planar surfaces of which one constitutes aboundary of the air gap separating the respective pole-pieces from thearmature and the other two surfaces are held in contact with spacingmembers which determine the length of the air gap in which the armaturevibrates. It is naturally important to secure accuracy in the length ofthe air gap and to have the faces bounding the air gap parallel and withdevices of small size, this is the more necessary and difficult toattain. The two pole-pieces then conveniently constitute main members ofthe framework of the relay and serve also to support the permanentmagnets, the signals coil and its core and the support for the vibratingarmature. The two cooperating members may then consist of flat plates ofidentical form, being set relatively at 180 de grees instead of beingmirror images of one another as has been common previously. The twomembers may be of opposite magnetic polarity with respect to thealternating or reversals flux set up by the signal currents if the relayhas a magnetic circuit according to Patents Nos. 1,826,- 990 and2,412,123 or they may be of opposite magnetic polarity with respect tothe polarising flux if a permanent magnet is sandwiched between them andthe armature vibrates within the signal or input current winding in amagnetic circuit similar to that described in the specification ofPatent No. 1,552,676.

The major extensions of the pole-piece members lie substantiallyparallel to one another and to the axis about which the armaturevibrates and on opposite sides of that axis. The armature is suspendedto vibrate about an axis near to its centre of gravity and to and fromthe polepieces.

Since the working gap in which the end or ends of the armature vibrateslies between the pole-pieces of magnetic material, its Width may be setaccurately by spacing the pole-pieces apart by spacing members whichmay, in some cases, be permanent magnets. The faces of the parallelpole-pieces may easily be set parallel to one another by accuratelyforming the spacing members.

The novel form of relay lends itself to the provision of compliantcontact mountings as set forth in Patent specification No. 2,219,222. Byproviding means for connecting the armature to a diaphragm instead ofproviding relay contacts,

any form of the magnetic structure may be used in a loud-speaking orother telephone receiver.

One important feature of the invention is that the two pole pieces areformed of flat plates of soft magnetic material and may be punched fromsheet stock.

In order that the invention may be more clearly understood and readilycarried into effect, some examples of electromagnetic instrumentsconstructed in accordance with the invention will now be more fullydescribed with reference to the accompanying drawings in which:

Figure 1 is a front elevation of one form of the invention as applied toa polarised telegraph relay;

Figure 2 is a plan of the same; while Figure 3 is an end elevation ofthe relay; and

Figure 4 is a perspective view of the chief elements of the relaydismantled; and

Figure 5 is a perspective view showing a modification of the magneticstructure according to Fig. 1.

Referring first to Figs. 1 to 4, the two polepieces I, 2 are identicaland each consists of a fiat plate with an arm 3 to form the pole-pieceproper, a shank 4 at right angles to the arm 3 and a projection 5opposite the shank 4 for carrying one of the bars 6 which serves as asupport for the fixed contacts I. The pole-pieces l, 2 are formed of asoft magnetic alloy of low coer civity. A spacing bar 3 of magneticmaterial is secured to one face of the pole-piece l or 2 in line withthe shank 4 and the permanent magnet 9 has its rear end fixed to thespacing bar 8 by a screw lil. Thus the permanent magnet 9 extendsparallel to the pole-piece I or 2 but staggered relatively to it by anamount equal to the thickness of the spacing bar 5. The two polepiecesl, 2 are rigidly secured together and set relatively at degrees to oneanother by a pair of non-magnetic screws H passing through bothpole-pieces near their ends and each en gaged by a nut Ha and having anon magnetic washer I2 around each screw II to serve as the spacingmembers between the two pole-pieces I, 2. The inner faces of thepole-pieces are ground flat and the two washers are ground or coined soas to be finished accurately to the predetermined thickness, forexample, of about a tenth of an inch so that the spacing washers I2accurately determine the length of the air gap between the polepieceswhich are secured together with their facing surfaces accuratelyparallel. Although in the example illustrated, the pole-pieces I, 2 areaccurately finished over the whole of their facing surfaces, what isactually important is that the areas of each of the facing surfaces incontact with the spacing washers I2 and that which forms a boundary ofthe air gap separating the pole piece in question from the armature areaccurately made as three co-planar surfaces with the result that thelength of the gap between those parts of the pole-pieces with which thearmature co-operates is accurately determined.

Owing to the staggering of the permanent magnets 9 relatively to therespective pole-pieces I, 2, the magnets 9 are mounted with their outerends which are of like polarity, parallel to one another but with eachrelatively on the opposite side of the armature I3 to the correspondingpole-piece I or 2. In the example illustrated, the armature I3 consistsof a strip of the section at the top seen in Figs. 2 and 4 and hassuspension blades I4 let into it in the neighbourhood of its centre ofgravity and extending from either side. Each suspension blade I4 isfixed by a screw I5 to a brass block I3, each of which is fixed to theinner face of the respective polepiece I or 2 by screws I6a, but whichare threaded into holes I! in the block I6 and holes I8 in thepole-piece I or 2. At its upper end, the armature I3 is formed with twooffset lateral extensions I9 each of which bears one of the movingcontacts 20 of the relay. By this arrangement, the overall effectivethickness of the armature is reduced and space is saved. The lower endof the armature is reduced and space is saved. The lower end of thearmature I3 lies in the gap between the limbs 3 of the pole-pieces andvibrates between those limbs.

The signals coil 2| embraces a laminated core 22 which abuts againstvertical laminations 23 at either end and the latter are pressed againstthe respective shanks 4 of the pole-pieces I, 2. This is effected byintroducing the shank 4, core 22 and laminations 23 into the spacebetween two uprights 24, 25 of a brass foot-piece 2B and clamping theparts in position by a screw 21, tapped into the upright 25. Thus thetwo limbs 3 of the pole-pieces I, 2 are of opposite polarities withrespect to the alternating flux produced by the signals current in thecase of a relay or by the movement of the armature in the case of atelephone transmitter or phonograph pick-up while the polarising fluxesfrom the permanent magnets 9 enter the armature from both polepiecelimbs 3, pass in parallel through the armature and return to the magnets9. It will be seen therefore, that in this example, the magnetic circuitis arranged generally according to patent specifications 1,826,990 and2,412,123.

The stationary contacts of the relay are seen at I on opposite sides ofthe armature and are carried on bent-out leaf springs 28 fixed at oneend to the support bars 6 and having each of the other ends free to rubon an adjustable screw 29 projecting from the bar 3 so that adjustable.4 damping is applied as in patent specification No. 2,219,222. The bars6 are rivetted to fiat springs 30 which are fixed by screws 3I to theprojections 5 of the pole-pieces I, 2 and are biassed or set to causethe bars 6 to bear on the ends of adjusting screws 32. The latter arescrewed in the split ends of the opposite spacing bar 8 and have heads33 enabling them to be adjusted by small tommy pins. The stationarycontacts 1 are thus located to co-operate with the moving contacts 2|carried by the armature as already described.

In the form of magnetic structure shown in Fig. 5, the two pole-piecesI, 2 are identical fiat plates of substantially the same form as inFigs. 1 to 4 with the limbs 3, shanks 4, and projections 5 but inaddition to the screws II and non-magnetic spacing washers, thepole-pieces are spaced by two permanent magnets 34 from two furtherpole-pieces 35 having major extensions 36 taking the places of the barmagnets 9. The polepieces I, 2, 35 are all made of a soft magnetic alloyof low coercivity. The permanent magnets 34 are formed of a recent formof magnetic material consisting of grains consolidated by a binder ofsynthetic resin and having a high coercive force and known under thename Cassalox."

They are magnetised to have unlike poles on their opposite faces so thatthe extensions 36 present tips of like polarity as marked N. Thearmature,

the relay contacts and the remaining parts are not shown but they are asshown in Figs. 1 to 4.

As shown in Figures 4 and 5 of the drawing, each pole piece is formed ofa main limb comprising the shank 4 and the vertical extension thereofwhich carries the projection 5, and an auxiliary limb 3 extending atright angles to the main limb at a point intermediate the ends thereof.

I claim:

1. An electromagnetic device for the interconversion of electrical andmechanical vibrations comprising, an energizing coil having a magneticcore, a pair of pole pieces formed of two flat plates of soft magneticmaterial and having main limbs arranged in parallel relationtransversely of the axis of said coil, one end of each main limb beingmagnetically connected with one end of said core, said pole pieces alsohaving auxiliary limbs extending from points intermediate the ends ofsaid main limbs at right angles thereto and in overlapping parallelrelation parallel with the axis of said coil, means securing saidoverlapping auxiliary limbs together in spaced parallel relationincluding a pair of spacers of equal thickness interposed between saidauxiliary limbs at spaced points along their length, the inner faces ofsaid auxiliary limbs between said spacers forming the bounding surfacesof an air gap having a length equal to the thickness of said spacers,and an elongated magnetic armature having one end thereof positionedwithin said air gap and extending in the space between the outer endportions of said main limbs, and means for pivotally supporting saidarmature from the outer end portions of said main limbs for vibrationabout an axis parallel with the axis of said coil.

2. An electromagnetic device according to claim 1 and including a barmagnet secured at one end to the outer end portion of one of said mainlimbs and extending at right angles thereto in overlapping relation withsaid armature substantially at the pivotal axis thereof, and a secondbar magnet having one end thereof secured to the outer end portion ofthe other main limb and extending at right angles thereto intooverlapping relation with said armature substantially at the pivotalaxis thereof and on the opposite side of said armature from said firstmagnet, each magnet being positioned on the op posite side of thearmature from the auxiliary limb carried by the main limb supporting themagnet.

3. An electromagnetic device for the interconversion of electrical andmechanical vibrations comprising, an energizing coil having a magneticcore, a pair of pole pieces formed of magnetic material of lowcoercivity and having main limbs arranged in parallel relationtransversely of the axis of said coil, one end of each main limb beingmagnetically connected with one end of said core, said pole pieces alsohaving auxiliary limbs extending from points intermediate the ends ofsaid main limbs at right angles thereto and in overlapping parallelrelation parallel with the axis of said coil, means securing said overlapping auxiliary limbs together in spaced parallel relation including apair of spacers of equal thickness interposed between said auxiliarylimbs at spaced points along their length, each of said auxiliary limbshaving co-planar surfaces forming seats for said spacers at said points,the inner faces of said auxiliary limbs between said spacers beingco-planar with the seating surfaces of said spacers and forming thebounding surfaces of an air gap having a length equal to the thicknessof said spacers, and an elongated magnetic armature having one endthereof positioned within said air gap and extending in the spacebetween the outer end portions of said main limbs, and means forpivotally supporting said armature from the outer end portions of saidmain limbs for vibration about an axis parallel with the axis of saidcoil.

4. In an electromagnetic device for the interconversion of electricaland mechanical vibrations, the combination of a pair of substantiallyidentical flat pole plates of magnetic material of low coercivity, eachplate being formed of a main shank and a transverse arm extending atright angles thereto, means supporting said plates with the shanksthereof in spaced parallel relation and with the transverse arms thereofin parallel overlapping relation, each transverse arm extending from itsown shank towards the opposite shank, each of said transverse armshaving three co-planar surfaces formed on the face thereof which facesthe other transverse arm, the coplanar surfaces on one of said armsbeing arranged opposite the co-planar surfaces on the other arm, wherebysaid surfaces are arranged in three pairs of opposed surfaces spacedalong said overlapping arms, said means supporting said plates includinga pair of spacers of equal thickness interposed between said transversearms at the two outer pairs of opposed surfaces and engaging saidco-planar surfaces, the spaced co-planar surfaces of the central pair ofopposed surfaces constituting the bounding surfaces of an air-gap havinga length equal to the thickness of said spacers, means connected betweensaid shanks and arranged parallel with said overlapping arms formagnetizing said shanks in opposite polarity, and a magnetic armaturepositioned within said air-gap and mounted for vibration lengthwise ofsaid gap.

5. In an electromagnetic device for the interconversion of electricaland mechanical vibrations, the combination of a pair of substantiallyidentical fiat pole plates of low coercivity, each plate being formed ofa main shank and a transverse arm extending at right angles thereto,means supporting said plates with the shanks thereof in spaced parallelrelation and with the transverse arms thereof in parallel overlappingrelation, each transverse arm extending from its own shank towards theopposite shank, each of said plates having three coplanar surfacesformed on the face thereof which faces the other plate. the co-planarsurfaces on one of said plates being positioned opposite the co-planarsurfaces on the other plate, whereby said surfaces are arranged in threepairs of opposed surfaces, two of said pairs of opposed surfaces beinglocated respectively adjacent the ends of said arms and the third pairsubstantially mid-way between said two pairs, said means supporting saidplates including a pair of spacers of equal length interposed betweensaid plates at the two outer pairs of opposed surfaces and engaging saidco-planar surfaces, the spaced co-planar surfaces of the central pair ofopposed surfaces constituting the bounding surfaces of an air-gap havinga length equal to the thickness of said spacers, means con nectedbetween said shanks and arranged parallel with said overlapping arms formagnetizing said shanks in opposite polarity, and a magnetic armaturepositioned within said air-gap and mounted for vibration lengthwise ofsaid gap.

RUPERT EVAN HOWARD CARPENTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,585,204 Pack May 18, 19261,624,476 Cummings Apr. 12, 1927 1,680,667 Curtis Aug. 14, 19281,786,479 Conover Dec. 30, 1930 1,872,257 Durkee Aug. 16, 1932 2,163,161Wadsworth June 20, 1939 2,215,782 Ellis Sept. 24, 1940 2,396,135 Terryet al Mar. 5, 1946 2,412,123 Carpenter Dec. 3, 1946 2,433,739 Collins eta1 Dec. 30, 1947

